Electrical outlet or junction boxes are commonly, if not universally, used in residential and commercial buildings as a means for holding electrical devices (outlets, switches, etc.), and for holding and/or guiding the electrical wires or cables that are attached to the electrical devices. Electrical outlet boxes typically comprise a rectangular, square, or octagonal metal or plastic “box” having one open side and a plurality of knockouts (partially stamped or scored portions that can be easily removed to form conduit or cable through-holes) on the other sides. Outlet boxes can be attached directly to a wall (“surface mounting,” oftentimes used in industrial settings), or they can be attached to the sides of a wall's metal or wood support members (studs or joists), with the interior of the outlet box being exposed by way of a hole in the wall covering (“flush mounting”).
For flush mount applications, the electrical outlet box must be somehow fastened to the side of a stud or joist. Frequently, this is done by angling a fastener screw or the like through the open front of the box, through an angled fastener aperture provided in one of the box's sides, and into the stud or joist. U.S. Pat. No. 6,100,469 to Jorgensen et al. shows such an outlet box. Alternatively, separate mounting brackets can be used, as shown in U.S. Pat. No. 4,572,391 to Medlin, or the electrical box can be provided with external mounting wings or brackets, as shown in U.S. Pat. No. 6,198,045 to Roesch.
While these attachment mechanisms are functional, they suffer from certain drawbacks. For example, angled fasteners do not work well with metal studs, require significant precision, and are relatively time consuming to use, while separate brackets can increase both cost and time (i.e., a separate bracket has to be purchased, which then has to be separately attached to both the box and stud). If the bracket is pre-attached, it must be set at the correct depth for the wall finish contemplated, leading to an inventory problem of many different preset depth box variations. Also, external mounting wings or brackets increase manufacturing costs, and, since they extend beyond the box body itself and are relatively bulky, greatly limit how the box can be oriented for attachment to a wall stud. This can be especially problematic when cables or conduit come at the outlet box at a particular angle, e.g., at a side where the box might not have the proper series of knockouts, if any at all, or the access is inhibited by the pre-attached bracket. The flange, or bracket, if placed on the front of the stud, as is common, also leads to aesthetic problems. It can create a bulge in the wall finish when Gypsum Board or “drywall” is used, the most common finish today.
More specifically, in wiring most modern buildings, there is oftentimes a mix of various types of wiring (armored or sheathed electrical cable, conduit, data lines, etc.), all of which may need to be routed to and/or through an outlet or junction box. Moreover, conduit is typically rigid, and cannot be bent in a small radius to accommodate misaligned conduit knockouts. Unfortunately, most electrical outlet boxes cannot easily handle a mix of multiple cables and conduit, and, even if they can, are relatively inflexible in terms of cable/conduit placement, e.g., the box can only accommodate vertical or horizontal conduit, but not both, or cable runs must be made up to look like conduit (box connectors).
Finally, many outlet boxes include cable clamps, which are attached to the interior of the outlet box by a screw extending through the clamp, through a tapped hole in the box, and out the back of the box. Ground screws, by which a ground wire is affixed to the box, also typically project past the back of the box. The mounting screw especially can be a problem when the excess, projecting thread hits another box (in back-to-back mountings), or hits a hard surface like a masonry block wall. Masonry requires the electrician to cut off the projecting screw after tightening it, which is problematic and time consuming. Also, the cable clamps: (i) are bulky, taking up a lot of space inside the outlet box; (ii) only provide one point for securing the cables, which can become dislodged or loose if pulled sideways; and (iii) are sharp and can cut wiring when it is pushed back inside the box.
Accordingly, a primary object of the present invention is to provide an electrical outlet or junction box with enhanced-performance cable clamps located on the exterior of the outlet box, thereby liberating interior space for cable connections and/or loop-throughs.
Another object of the present invention is to provide such an electrical outlet or junction box with a design that retains clamped cable in at least three places along its axial length.
Another object of the present invention is to provide such an electrical outlet or junction box that can be quickly and easily affixed to the side of a stud or joist, and especially to metal studs, without causing a drywall bulge.
Another object of the present invention is to provide such an electrical outlet or junction box that can be oriented to align with incoming conduit while still accommodating a mix of multiple cables and conduits, even on the same box wall.
Another object of the present invention is to provide such an electrical outlet or junction box with screws or studs extending inwardly, toward the finish wall surface, for ground and cable clamp retention, so as to eliminate excess thread extending past the back of the box.